1. Field of the Invention
The present invention relates to a KVM switch which is directly connected to a server and connected to a client via a network, as well as a method for controlling the same, and in particular to a KVM switch which causes a display device connected to the client to display an image signal output from the server, as well as a method for controlling the same.
2. Description of the Related Art
Conventionally, there has been known a KVM (K:keyboard, V:video, M:mouse) switch which is connected between a plurality of computers and peripheral devices such as a mouse, a keyboard, and a monitor (see e.g. U.S. Pat. No. 6,567,869).
Conventionally, there has been known a KVM switch which is connected to a plurality of servers and peripheral devices such as the mouse, the keyboard, and the monitor, and is connected to a client which is a remote terminal via a network (See e.g. Rose Electronics Ltd., products name “UltraMatrix Remote”.
In a server-client system including the KVM switch, an image from the server is displayed on a monitor connected to the client via the KVM switch and the network.
Further, conventionally, there have been known a signal processing apparatus which thins out pixels like a checkered pattern to decrease data to be compressed, and achieves compression and extension processing of an image with high speed and low cost (see. Japanese Laid-Open Patent Publication No. 2006-340300), a recording device which sets a thinning-out rate of dots, and records an image on a sheet by the set thinning-out rate (see. Japanese Laid-Open Patent Publication No. 09-34244), a television system in which a signal transmission side divides image information into two pieces of field information comprised of odd number scanning lines and even number scanning lines and transmits them to a signal reception side, and the signal reception side synthesizes two pieces of received field information to create image information of one frame (see. Japanese Laid-Open Patent Publication No. 59-54394).
However, when the image data always changes like a moving image in the above-mentioned server-client system, the image data for all screen area is transmitted from the server to the client via the KVM switch and the network.
Therefore, it takes time to transmit the image data from the server to the client. Moreover, the communication band of the network is occupied by the transmission of the image data from the server to the client, so that processing to transmit operation data of an input device connected to the client to the server is delayed.
Further, even if the image data transmitted from the server to the client is thinned out, it might still take time to transmit the image data. As a result, processing to transmit operation data of an input device connected to the client to the server is delayed.